1. Field of the Invention
The present invention relates to a method and system for processing data in a memory area of an IC card.
2. Description of the Related Art
In recent years, an IC (Integrated Circuit) card which incorporates an IC chip constituted by an erasable nonvolatile memory and a control element such as a CPU (Central Processing Unit) has attracted attention as a new portable data storing medium. This IC card causes the control element to access the memory and selectively performs data input/output for an external apparatus.
In order to use this IC card in various applications, the memory is divisionally defined as a single command data file and a plurality of application data files, and each data file is divisionally defined as a plurality of areas.
Access to these areas can be performed by designating specifying data such as an area number provided to each area. The areas in a data file are accessed by designating specifying data such as a data file name affixed to each data file and selecting that data file.
According to such an IC card, data files are defined together in advance. Therefore, at the time of using an IC card, when all the applications to be used are not known, data files cannot be defined. Conventionally, the total size of definable data files is not known, so that data files could not defined. This prevents additional definition of data files.
According to this IC card, a plurality of passwords are stored in a memory. An externally input password is checked with the passwords stored in the memory, and enabling/disabling of access to an area is determined in accordance with the check result.
If specifying data provided to passwords and specifying data provided to areas are set so that the former data differ from the latter data, the number of areas set to a memory would influence the number of passwords set. This restricts the specifying data in use.
Access to an area in an application data file is performed by selecting a application data file in which the target area exists. It should be noted that access to areas in a common data file is possible irrespective of whether or not an application data file is selected. For instance, if areas in a common data file and those in an application data file can be accessed by the same command data, it is necessary to distinguish the specifying data for the common data file from that for the application data file. This necessitates to alter the check process depending on systems.
In view of the above circumstances, there is a demand for an IC card which can process data in memory areas with high efficiency.